Manufacture of steel.



UNITED S TES PATENT orricn.

JEGOR ISRAEL BRONN,'OF BOMBACH, GERMANY, ASSIGNOR OF ONE-HALF TO THE FIRM 3 OF BOMBAGH ER H'U'TTENWEBKE, QF ROMBAGH, GERMANY.

MANUFACTURE .OF STEEL No Drawing.

To all whom ita nag concern:

" Be it known that I, Jncon ISRAEL BRONN,

a citizen of the German Em ire, and resithird, dissolving in said secondary molten charge the necessary additional elementsin proper proportion for the steel to be made 'fronrth main charge,-and finally m 1x1ng the mainandsubsidiary charges WhIle in I molten condition. Otherwise stated the addeoxida tion,

elimination of gas or alloying with'other ditions which it is desired to make to the bath; of a refined iron for the purpose of desulfurization, carburation,

metals, arefirst dissolved in liquid iron contained'in a separate furnace, and then the resulting dilute molten solution of the: said additions iii-the" molten iron is poured together with the bath of refined iron into the casting ladle wherein they become mixed together. l/Vhen the refining furnace is so constructed that the slag covering can be removed from the main iron bath (for in I stance in tilting furnaces), the molten solution-of iron may also be added to the main bath. contained in the refining furnace after having previously removed the slag covering from the latter. It is advisable'to use refined (soft) iron of the greatest possible purity as the solvent in order that no undesirable constituents shall be added to the main iron bath through the medium of the solvent. Now since such refined iron is alavays available in the molten state in steel- .ivorks, it is advisable, for the sake of saving the cost of remelting, to charge the dissolving furnace (which can be heated by gas, oil, or electricity) with such liquid iron, and to dissolve therein the desired additions (for instance carbon in the form of powderedcoke, coke briquets, or carburite, or metals such as manganese, silicon, titanium, vanadium, tungsten, chromium) either in the pure state or in the form" of ferro-alloys mixed in the desired proportions. By this means a solution is produced containing one Specification of Letters Patent. Application filed December 2, 1912. Serial mi. 734,614.

Patented Oct. 12, 1915.

or more of'these constituents in exactly determined quantities and groupings, and this solution is mixed with the main bath ofrefined iron.'. This improved method will now bedescribed more fully with reference'to examples and will'be compared with existing methods. Eor instance, for the purpose of effecting carburation according to the new process, liquid iron is saturated with carbon-at the. highest possible temperature in a dissolving furnace by the addition of coke, carbon briquets, or other carbonaceous mixtures, thus producing a molten solution of iron containing exactly determinable quantities of carbon. i.

To prepare a" charge of steel'having a certain percentage of carbon, the correspondingquantity of iron-carbon is taken from the dissolving furnace and is introduced While still liquid into the steel forming charge that is to be prepared, care being taken to remove theslag covering therefrom.

For instance, if it is desired to 'make a 10 ton charge f Thomas, Bessemer, or Martin steel contalnlng 0.6% of,carbon, that is, a total content of 10 16 =60 kgs. of carbon, it" will be necessary -to take 60 1.11 tons 54 of molten metal from the dissolving furnace because each ton of 0.6% carbon steel contalns 606:54 kgs.

of carbon. Thus the improved process admits of production with certainty, from ordlnary. Bessemer, Thomas, or Martin in- ,got iron, at a very low cost, pure carbon steel of extraordinarily uniform quality even when dealing with very large charges. Heretofore when it has been desired to produce carbon steel it has been usual to I corporated again in the ironbath.

of which theconstituents of the slag, more especially phosphorus are reduced and in- That method occasions great lossof time because the operator must wait until the carbon has become dissolved and it is impossible to know beforehand exactly how. much carbon is taken pp by the iron, and'further there is the risk-that the noxious constituents of the slag may be taken up again by the iron. Now in order to avoid these subsidiary reactions it hasalso been proposed to ii1troduce the carbon subsequently with the ingot iron into thecasting ladle. It is however obvious that that method cannot yield a homogeneous product of uniform quality and composition.

Another example For the purpose of making manganese steel according to the improved process, manganese or, ferromanganese is dissolved in the liquid iron contained in a dissolving furnace; and the solution is mixed with the main charge of the steel to be made. In order to make a manganese-carbon steel containing a given percentage of carbon and manganese, the

corresponding quantity of carbon is dissolved in the dissolving furnace at the same time as the ferro-manganese. It has heretofore been usual to make such steels by means of spiegeleisen. In such a case a charge of about 25 tons of medium hard steelwill require about 2000 kgs. of spiegeleisen containing 10% of manganese and about 4.5% of carbon. In order to obtain the requisite 200 kgs. of manganese and 90" kgs. of carbon the steel maker will have to buy 1700 kgs. of outside iron which will naturally cost him much more than the iron he makes himself, and he will have in addition to pay ten times the cost of carriage. To obtain the iron in themolten state it will also be necessary to melt down the whole 2000 kgs. which will, entail a great consumption of fuel, or, in the case of an electric furnace, a-great consumption of electrical energy. Now with .the improved process the state of affairs isquite difl'erent:-Here, since, as already stated, every steelmaker always has liquid ingot iron available in large quantities, about 1750 kgs. of this ingot iron are charged while liquid into the dissolving furnace 250 kgs. of form-manganese with of manganese and also if required the desired quantities of carbon, 'ferro-silicon and the like are dissolved with application of heat and the solution is now ready for use. The

nece'ssaiy consumption of heat or energy is with the steel charge to be made. The ii solvent iron.

tain no constituent other than manganese for instance, or which are to contain a number of reagents together (for instance carbon, silicon, etc.) canbe produced with any desired groupings or proportions of such constituents, If aswas often the case heretofore spiegeleisen was added to the previously refined steel chargethe same disadvantages were experienced as in the process of carburation in the furnace but "in a very much greater degree, namely delay in the finishing of the charge, subsidiary reaction with the slag covering so that a part of-the valuable manganese was lost in the slag, and moreover the constituents reduced of or in addition to carbon and manganese it is desired to addother metals to the steel charge either for the purpose of refining it or producing alloys. :For instance if it is desired to make a steel containing chr-y mium, nickel, manganese and carbon, the

liquid iron present in the dissolving furnace is mixed with theseingredients in the desired proportions, and when the whole mass has become molten the 50111131011 1s I111?! contained in. the dissolvingfurnace serv as above stated, as a solvent vehicle for the reagents that are to be added. The purer this solvent the greater the freedom of the operator in grouping the subsidiary constituents. In some cases however a perfect purity is of less importance as'regards the If it is desired for instance to make the carbon steels hereinbefore described, foundry cast iron of the greatest possible purity containing already about 2.5% of carbon may -be employed instead of the soft ingot ironabove referred to. p The advantages of the improved process are due to thesimultaneous co'ciperation of several factors the chiefof which are the following I (a) The different additions are added to the steel bath in a manner which precludes the loss of the active constituents, for instance by volatilization, formation of .slag

' and oxidation such as "often occurs with existing methods.

(b) Theease with which steels of any desired composition and grouping of the constituents may be produced, for instance, carbon steels which "are almost free from manganese or steels poor in carbon but rich in manganese. Heretoforethis has been very much more difiicult because for instance in spiegeleisen as also in ferro-manganese the proportion between the contained percentage of manganese and the contained percentage of carbon is almost fixed and this mutual dependence of the two elements affects also the finished products.

' facture steels of complex composition with 1 be dissolved aiidlbecome. uniformly distrib-.

heretofore unattainable exactness and precision.

(rl) The molten state of the subsidiary] charge guarantees the uniform action and distribution of the several constituents the'main char e; p '(e) .By-the use quantity of the constituent to be added,' 'the risk of congealing during the various Inanip ulationsis]avoided. Thus, for instance,- heretofore in makingyanadium steelandi titanium steel usually only a ,very small per- 4 centage of theseT 'nietals or their alloys was addedv in solid form to the 'steel' charge, it

being assumed: that the said. percentage will uted thr'oughoutth'echarge Without residue. Such is howeirer not the case and this is no doubt the-cause of many failures that have gbeen experienced with these steels 1 Even if it were attempted to meltthese constituents beforehand as is often done now in the.

casefiof ferro-manganese, success is not certain, because since only small quantities of v say; 20. kgs. are dealtwith inthis'case such small'qu'antities of molten metal-would congeal on -the way from the meltin'g'furnace to the place of use, while the meltingof such valuable metals is attended by heavy 3 loss in consequence-of their great tendency to oxidation, (formation of; slag).

(f)- The addition of a relativelyi large quantityof; highly heated molten iron with the constituentsdissolved therein not only does not withdraw any'heat from the steel charge, as the case when the additions are.

of a quantity of highly) heated metal, many times. greater than the T which consists in melting aquantity of iron, adding to it manganese or a manganese althrown injsolid buteven adds an increment of heat to. the steel charge.

What I claim is 1. The process of manufacturing steel additions solid form into a quantity of liquid iron,,viand mixing the solution so obwhich consistsin introducingthe required tained with the refined molten iron constituting the main steel making charge.

2; The process of manufacturing steel tained with the main charge of molten refined iron. I t Y 3. The process of -manufacturing steel which consists in melting a quantity of refined iron, adding to it carbon in desired proportions and mixing the solution so ob- "tained with the main charge of molten refined iron.

4 The process of making steel, which consists in refining and decarburizing a main charge of iron in a suitable furnace,-

forming a subsidiary charge by introducing in solid form and dissolving vthe additional constituents of the ultimate steel in properproportions in a bath. of molten refined iron, and mixing'the mainand subsidiary charges while in a molten. state.

' In testimony, Y t] at I claim-the foregoing as my invention, I have signed ny'name in presence of two'wi'tnesses, 20 day of,

Noy'emben 1912-. H

- JEGORIISRAEL BRONN.

witnessesz ID A ALLMANN-BRONN,

JACOB SCHMIDT-i 

